Context:

• A randomised trial has shown two candidate drugs to be highly effective in curing Ebola, especially if treatment is started early.

Background:

• In 2018, Ebola struck the Democratic Republic of the Congo (DRC), making 2,619 people ill and killing 1,823 (overall fatality rate of about 67%).
• The first step towards finding a cure was taken in 2005 by veteran Congolese microbiologist Jean Jacques Muyembe Tamfum, who helped discover Ebola virus in 1976 and is now tasked with bringing the current outbreak under control.
• Tamfum transfused blood of Ebola survivors into eight people with disease and though antibodies were not isolated, seven of the eight survived.
• In 2006, antibodies isolated from two survivors led to the development of mAb114.

Details:

• Earlier, Merck’s preventive Ebola vaccine (rVSV-ZEBOV-GP), which has had a 97.5% efficacy, helped slow the virus’s spread, but was not able to stop the disease in its tracks.
• Now, four candidate drugs — Zmapp, remdesivir, REGN-EB3 and mAb114 — have been tested in a randomised trial.
• Preliminary results, of nearly 69% of the total number of participants show that two of the candidates, REGN-EB3 and mAb114, were highly effective in treating people infected with the virus.
• REGN-EB3 is a cocktail of three antibodies generated by injecting Ebola virus into a mice model that has a human-like immune system.
• mAb114’s development goes back to the Ebola outbreak in 1995 in Congo.
• The overall mortality among patients randomly chosen to receive REGN-EB3 and mAb114 was 29% and 34% respectively.
• Further, REGN-EB3 cured the disease in 94% of such patients, while, in the case of mAb114, it was 89%.
• In the case of Zmapp and remdesivir, the overall mortality was way higher at 49% and 53% respectively.
• The striking difference in efficacy was in patients who were recently infected (and so had a low viral load).

Challenges:

• A high coverage will be required to prevent future outbreaks.
• When an outbreak occurs it is difficult to trace primary contacts and contacts of contacts
• There is mistrust among the infected people towards authorities and health-care workers.
• We will have to wait till end September or early October before final analysis of all the trial data is performed.

Source:TH